Engine cooling baffle



June .7, 1949. A. T. GREGORY 2,472,418

I ENGINE COOLING BAFFLE I Original Filed Dec. I, 1943 2 Shets-Sheet 1 BY W %jv z a June 7, 1949. A. T. GREGORY' 2,472,418

I ENGINE COOLING BAFFLE Original Filed Dec. 7, 1943 2 Sheets-Sheet 2 ATflfi/YEYS Patented June 7, 1949 QFFICE ENGINE COOLING BAFFLE ()riginalapplication December 7, 1943, Serial No.

Divided and this application January 29, 1945, Serial No. 575,083

8 'illaims. 1

This invention relates to baffles for internal combustion engine coolingsystems, of the general type described and claimed in my applicationSerial No. 513,211, filed December 7, 194:3, now abandoned, of whichthis application is a division.

In accordance with the present invention, the differential air pressurecooling system described in said application, as adapted foraeronautical engines, comprises a main static pressure cooling airscoop, supplemented with a conduit system, or two air scoops andcorresponding conduit systems, whereby large volumes of cooling air aredirected on opposite sides of the finned cylinders of a row or bank,under such conditions that the system is bipolar in operation. The airoutlets from such bipolar conduits or passages aggregate a smaller areathan the area of the scoop air intake opening or openings, or,alternatively, a restriction to air flow as by friction is created, sothat a substantial pressure builds up Within the scoop, owing to thekinetic energy of the inflowing air, and hence the cooling air that isbipolarly directed by the system over the selected areas of the cylindersurfaces flows at substantial volume, pressure and velocity.

In addition to selected areas of the cylinders that are cooled by thelarge volumes of cooling air conducted thereto by the bipolar system,certain more localized areas thereof require special cooling by reasonof hot spots, piston thrust frictional heat, and the like, and it is theprincipal object of the present invention to provide baflle means atsuch localized areas to effect special cooling thereof.

In accordance with the present invention, a sharp-edged bafile isinserted part way into the cooling sins of the cylinder so as topartially .intercept the cooling air stream such as that issuing .fromone of the bipolar ducts, thereby creating turbulence in the stream asit flows over the sharp edge of the baffle. The baflle is so placed thatthe turbulence is created at the local area requiring special cooling,so .that the turbulent air scours the adjacent cylinder wall and fins tothereby remove the heat and also the skin .of spent cooling air thattends to adhere to these areas.

'Figure 1 is a vertical section through an inverted inline aeronauticalengine equipped with theloca'l turbulence-creating cooling baffle ofthis invention, as seen along the line 1-1 of Fig.2;

.Fig. 2 is a horizontal section therethrough as seen "along the line 2-2of Fig. 1 only three cylinders being shown; and

Fig. 3 shows another manner in which the local turbulence-creatingbaflle may be made.

Referring to Figs. 1 and 2 of the drawings, numeral 8 designates aninverted inline aeronautical engine to which the invention may beadapted, and having a bank of cylinders 9, which may be six in number,provided with the usual intake and exhaust pipes Ill and l I,respectively.

The barrels i2 and the heads 13 of the cylinders constituting the bank 9are provided with the usual horizontal cooling fins It, the head beingprovided with additional cooling fins t5 extending longitudinally of thecylinder bank '9 as shown. "The crankcase l6 and the camshaft hous- 'ingll are positioned above and below the cylinder bank 9 according to theusual construction of inverted i-nline engines. One side of the engine 8is provided with the scoop it having an opening 258 directed in thedirection of travel of the engine and preferably located in theslipstream of the propeller for collecting a portion of the air stream,the top 2!, bottom 22, and end of the scoop It being sealed so as toform a substantially closed chamber into which the air flows, thischamber being designated 23 and being located at one side of thecylinder bank 9, as shown.

Extending upwardly from the bottom 22 of the scoop [.9 along the leeside of the cylinder bank '9, is a series of conduits or stacks 24, onefor each cylinder, as shown in Fig. 2. Each stack 2 tapers upwardly andis provided with an outlet slot 25'directed in the direction of theadjacent cylinder barrel l2, this slot 25 being defined by two flanges26 and 27 and extending the full height of the cylinder, including thebarrel l2 and head I3, and being narrow with respect to the diameter ofthe stack or conduit 2'4, 1. .e., the cross-sectional area of stack 2-4at any horizontal plane is greater than that of the slot 2,5 in thatplane, as seen in Fig. 2.

Flange 26 is continued around the lee side of the cylinder to form thebafile 28! having an outwardly turned lip 29, this bafile 28 preferablyeither being in contact with the tips of the Cylinder fins [4, as shownin Fig. 2, or very close to them.

The other flange 21 is turned inwardly toward the axis of the cylinderin the general radial direction with the tip 3! extending part waythrough .the cooling fins it so that its sharp edge is spaced from theouter surface of the cylinder barrel l2, thus providing a passage aroundits edge through which some of the cool air delivered at high pressurethrough the slot 25 flows to join the lower pressure cross streamflowing between the cylinders. The baflle 21, 3| thus formed constitutesthe turbulence-creating baffle of this invention, in conjunction with apressure cooling air stream, which the sharp free edge of the bafile 21,3| partly intercepts, thus causing turbulence in the air stream at thatpoint, as shown by the arrows in Fig. 2. This turbulent air scours thesurfaces of the cylinder fins I4 and barrel surfaces, removing the spentcooling air which clings thereto and also supplying fresh cooling airwith great rapidity to more effectively cool this localized area of thecylinder.

The tip 3| or edge of the baffle may be a straight edge on the flange 21and the fins I4 may be provided with an axial saw out 32 in which thetip or edge 3| is inserted, as shown in Figs. 1 and 2, or the tip 3| maybe serrated as shown in Fig. 3, with the uncut portions or projections33 extending between the fins I4. Obviously, the fins I4 may be saw outonly to half the depth of penetration of the tip or edge 3|, and the tipor edge 3| partly serrated, if desired. Although the off-center positionof the conduits 24 shown in Fig. 2 is preferred, conduits may be locatedat the center of the corresponding cylinders with substantially equal,and in some cases better, cooling effect, and the turbulence-creatingbaffle 21', 3| may be placed at any point requiring special cooling,substantially radially of the cylinder or at an angle to the cylinderradius, as shown,

A similar group of conduits 24 with turbulencecreating baffles 2'1, 3|may be positioned adjacent the upstream or front side of the cylinderbank 9 as disclosed in said application to secure the desired bipolarcooling, or a plate 34, having spaced vertical slots 35, withturbulence-creating edges 36, preferably located opposite the axes ofthe corresponding cylinders of the bank 9, may be employed as shown inFigs. 1 and 2.

As in the case of the passages 25 of conduits 24, the aggregate area ofthe openings 35 in the front plate 34 may be less than the air intakeopenings of the scoop I9, or, the outflow of air may be otherwiserestricted or retarded, as by making the combined areas between baffle28 and flange 21 and the cylinder wall less than the area of the slotleading thereto. Accordingly, a substantial static pressure builds upWithin the scoop chamber 23, owing to the kinetic energy of theinflowing air, so that the air issuing from slots 35, in the frontbaille 33 and from slots 25 in the stacks or conduits 24 flows atsubstantial velocity and pressure over the adjacent areas of thecylinder, in the direction of the arrows shown in Fig. 2. Owing to theshape of the flange 21 and baffle 23, the air issuing from the slots 25of the conduits or stacks 24 not only flows at substantial velocity overthe cylinder fins I4 and surfaces of the cylinder head and barrel, butit is caused to flow between the fins around a substantial portion ofthe lee side of the cylinder by reason of being confined between thecylinder barrel I2 and the baflle 28 and also against the cylinder andbetween the fins as it flows out around the tip 3| of the flange 21, Theturbulence created by the tip has a scouring effect, thus efiicientlycooling the cylinder at this point.

The cooling air is thus divided bipolarly, emerging from both openings25 and at opposite sides of the cylinders, so that these hotter sidesare scrubbed and cooled first by the large volume of cool air and thisair then cools the other sides or intercylinder surfaces requiring lesscooling. The construction of the air-intercepting baiiles 21, 3| andtheir location with respect to the cylinders and fins is such thatlocalized areas of the cylinder requiring special cooling will beeffectively cooled as required. Furthermore, the construction of thebaffles 21, 3| is such that the cooling air is constrained to flow overthe entire depth of the fins so that the entire fin from root to tip iseffective in rejecting heat to the cooling air.

The spent cooling air entering the lower pressure area 31 between thecowling 38 and the lee side of th cylinder bank, externally of thestacks or conduits 24, is preferably withdrawn therefrom by gills 39 orother eduction means in accordance with the usual practice, these gills39 being located in the slipstream to create suction.

While I have disclosed my invention as applied to a multiple cylinderengine of the inline type and in a bipolar cooling system, it is to beunderstood that the invention may be practiced in connection with radialtype engines and with one or any number of cylinders, and that I reservethe right to all changes in form and to all applications of theinvention falling within the principles of this invention and the scopeof the appended claims.

I claim:

1. Li a bipolar cooling system for an engine comprising a row ofcylinders, the combination of at least one air scoop having an intakeopening for receiving air under pressure, means on each side of saidcylinders in communication with said scoop and provided with restrictedpassages having outlets extending substantially along the lengths ofsaid cylinders at opposite sides thereof for directing air upon selectedareas thereof, the air directed against the areas of said cylinders onon side of said bank of cylinders following the surface of saidcylinders and flowing as a cross stream between the cylinders to a lowpressure area, and said outlets on the other side of said bank ofcylinders comprising flanges having their ends terminating at themargins of said areas on said side of said cylinders and at pointsspaced from said cylinders.

2. In a bipolar cooling system for an engine comprising a row ofcylinders, the combination of at least one air scoop having an intakeopening for receiving air under pressure, means on each side of saidcylinders in communication with said scoop and provided with restrictedpassages having outlets extending substantially along the lengths ofsaid cylinders at opposite sides thereof for directing air upon selectedareas thereof, the air directed against the areas of said cylinders onone side of said bank of cylinders following the surfaces of saidcylinders and flowing as a cross stream between the cylinders to a lowpressure area, and said outlets on the other side of said bank ofcylinders comprising flanges having their ends terminating at themargins of said areas on said side of said cylinders and at a pointspaced from said cylinders, one of said flanges extending along saidcylinder to one edge of said space, and the other of said flangesterminating at a point at the other edge of said area and at a pointcloser to said cylinders.

3. In an internal combustion engine having at least one cylinderprovided with cooling fins and transmitting a greater degree of heat atat least one point than around the remainder of the cylinder duringoperation of the engine, the combination of means for conducting astream of air to said cylinder, and baflie means having a sharp edgeextending substantially radially partly arough said fins adjacent saidpoint for partially intercepting said air stream to create turbulencetherein at said point, whereby the turbulence created thereby in the airstream occurs immediately at and between the fins at said point.

4. In an internal combustion engine having at least one cylinderprovided with cooling fins, the combination of means for conducting astream of air to said cylinder at a point thereon tending to overheatduring operation of the engine, and

baille means having a sharp edge projecting inwardly toward said finsfor partially intercepting said air stream to create turbulence thereinat said point, the edge of said bafile means over which the air flowsbeing positioned between the tips and roots of said fins, whereby theturbulence created thereby in the air stream occurs immediately at andbetween said fins at said point.

5. In an internal combustion engine having spaced cylinders havingcooling fins and adapted to be located in an air stream, the combinationof an air scoop for substantially enclosing one side of said cylindersand having an opening for directing a portion of the air stream intosaid scoop, means cooperating with said cylinders and forming with saidscoop a substantially closed chamber in which the air entering saidscoop builds up a substantial pressure, said means providing restrictedpassages for guiding pressure air streams at relatively high velocityover the cylinder surfaces and out of said chamber, and baffle means insaid chamber having relatively sharp free edges projecting toward saidcylinders and partly through the fins thereof and extending into saidstreams flowing through said openings over said cylinder surfaces forcreating turbulence in said streams.

6. In an internal combustion engine having at least one cylinderprovided with spaced cooling fins and having a point which tends tooverheat during operation of the engine, the combination of means forconducting a stream of cooling fluid across said fins substantially in adirection parallel thereto, and a baffle positioned transversely of saidstream in a plane extending substantially through the axis of saidcylinder with its free edge positioned between the roots and tips ofsaid fins to provide a reduced fiuid passage between said baiiie edgeand the adjacent wall of said cylinder at said point, whereby the bafiiepartially intercepts the flow of said cooling fluid between said fins tocause it to traverse the same from root to tip in its fiow through saidpassage and to create turbulence therein at said point.

7. In an internal combustion engine having at least one cylinderprovided with cooling fins, the combination of means for conducting astream of air to said cylinder, and baflle means having a sharp edgeextending substantially radially partly through said fins for partiallyintercepting said air stream, whereby a portion of said air stream flowsturbulently between the fins and through the space between said sharpedge and the wall of said cylinder to increase the cooling efiect 0f theair at that point.

8. In an internal combustion engine having at least one cylinderprovided with cooling fins, the combination of means for conducting astrearr of air to said cylinder, and baflle means having a sharp edgeextending substantially radially partly through said fins to apredetermined depth for partially intercepting said air stream, wherebya limited air stream flows between the fins and over said sharp edge toa predetermined depth to increase the efiectiveness of the fins indissipating the heat from the cylinder.

ALFRED T. GREGORY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,480,866 Smith Jan. 15, 19242,004,040 Dintilhac June 4, 1935 2,070,565 Dintilhac Feb. 16, 19372,152,043 Gregory Mar, 28, 1939 2,182,866 Gabrielson Dec. 12, 19392,289,959 Gregory July 14, 1942 2,424,416 Piry July 22, 1947 FOREIGNPATENTS Number Country Date 502,864 Great Britain Mar. 23, 1939

